/Engine/Source/Runtime/Engine/Classes/Animation/BlendProfile.h
Calculate the blend weight for a given bone. This methoid basically defines how each blend profile mode works.
static float CalculateBoneWeight ( float BoneFactor, EBlendProfileMode Mode, const [FAlphaBlend](API\Runtime\Engine\FAlphaBlend) & BlendInfo, float BlendStartAlpha, float MainWeight, bool bInverse )